1. The Field of the Invention
The present invention relates generally to the connection, combination and extension of adjacently stacked, modular expansion cards in electronic devices through the use of a novel electrical connection between the expansion cards. Preferred embodiments of the present invention relate more specifically to the connection, combination and extension of PC Card Standard expansion cards or expansion devices which are commonly stacked adjacently and in close proximity in a host portable computer. Specific embodiments of the present invention allow the use of multiple expansion cards which can communicate directly with each other and allow the use, by a second card, of connectors, antennas, cords, and other items located within a first card.
2. The Relevant Technology
Many computers, printers and other electronic devices utilize expansion cards to increase memory, add new features, increase capability and otherwise improve the functionality of the host device. Successful manufacturers in the computer industry allow for this increased functionality by providing expansion card slots in their products.
These slots are commonly constructed according to a known standard with well defined specifications so that third party expansion card developers may design products for the manufacturer""s host computer or other device. One standard, commonly used in desktop computers at the present time, is the Peripheral Component Interconnect bus architecture (PCI). This standard, like many others, defines the physical constraints of a compliant card including overall size and physical attributes of the electrical connectors on the card. Electrical parameters are also defined so that industry participants may design products that will work effectively with other manufacturers"" products.
The PCI standard is typically used in desktop computers to provide for the functional expansion of the host computer by allowing for the addition of modems, video cards, network adapters, sound cards, storage devices as well as other standard and customized features. In an ordinary desktop personal computer, the PCI bus architecture provides plenty of space around and between the expansion cards for wiring and interconnection of the cards. Simple ribbon connectors are commonly used for interconnection of PCI cards to other devices or other cards. While the PCI standard is common in bulky desktop computers, it is not typically suitable for smaller format devices such as laptop computers, notebook computers or Personal Digital Assistants (PDA""s).
These smaller format computers and electronic devices compete to be the smallest, lightest and most portable while offering the most capability and expandability. Consequently, their expansion card formats are much smaller and more compact than those used for desktop computers.
One expansion card standard for smaller format computers is known as the PC Card Standard. The PC Card Standard is promulgated by the Personal Computer Memory Card International Association (PCMCIA) which publishes and maintains the standard. The PC Card Standard comprises physical specifications for expansion cards as well as electrical specifications and connector requirements. A PC Card Standard card has a width of 54.0 millimeters and a standard length of 85.6 millimeters. The thickness of PC Card Standard cards varies with the xe2x80x9ctypexe2x80x9d of card. Thicknesses vary between 3.3 millimeters, 5.0 millimeters and 10.5 millimeters for Type I, II and III cards respectively. Currently, the Type I cards are used primarily for memory devices such as RAM, Flash, OTP, and SRAM cards. Type II cards are typically used for I/O devices such as data/fax modems, network adapters and mass storage devices. Type III PC Cards are used for thicker components such as rotating mass storage devices. All of the PC Card Standard compliant cards use a standard 68-pin connector to interface with the host device.
While the PC Card Standard serves well for a multitude of applications, it""s size restrictions and connector standard can preclude some finctionality. One aspect of the PC Card Standard and other thin architecture standards that can be problematic is their connection to an external device or network. This is commonly encountered in Type II modems or network cards which must connect to RJ-11, RJ-45 or similar plugs. These industry standard plugs are thicker than the PC Card Standard cards so adapters must be used to accommodate the thicker plugs. One ingenious method for accommodating the RJ type plugs is the XJACK(copyright) manufactured by 3Com, Inc. of Salt Lake City, Utah. The XJACK(copyright) is generally a retractable jack which may retract into the PC Card Standard card or protrude from it exposing an aperture in its body which will accommodate a standard RJ type plug.
While the XJACK(copyright) provides an excellent connection to a PC Card Standard device, its retractable configuration can consume a large amount of real estate within the card. Other retractable connectors have similar problems. Various xe2x80x9calligatorxe2x80x9d type jacks also retract into the expansion card thereby taking up space and precluding the use of that space for other purposes.
This problem is exacerbated in combination cards which have multiple uses. A common combination card is the modem combined with a network adapter such as an Ethernet adapter. This type of combo card has a need for two external connections: one to connect the modem to a phone line; another to connect the network adapter to a network. This is typically accomplished with an RJ-11 jack and an RJ-45 jack on a desktop computer, but standard RJ jacks will not fit on thin architecture cards. An XJACK(copyright) for each connection would be necessary, however this is not always possible. The XJACK(copyright) works well on single use cards, but two XJACK""(copyright) can consume a prohibitive amount of space in a single thin architecture card such as the PC Card Standard cards, especially the Type I and II cards.
One method used to at least partially overcome this problem is the proprietary connector or xe2x80x9cdongle.xe2x80x9d The dongle is a short cable fitted with a thin proprietary connector on one end which connects to a thin proprietary jack on a thin architecture card. The other end of the dongle is fitted with a housing which contains a standard RJ type jack. These dongles act as adapters to convert the cables with standard RJ plugs to the proprietary thin connectors which can be used with thin architecture cards. While the dongle provides an adequate connection, they are easily lost, tangled or damaged. The businessman stranded without a proprietary modem connection cable while on an important business trip quickly comprehends the drawbacks of the dongle concept.
In addition to the physical size restrictions imposed upon PC Card Standard cards and other thin architecture devices, the connector restrictions of these standards also inhibit some devices and combinations of device from conforming with the standards. The PC Card Standard requires a 68-pin connector with the function of each pin being designated in the standard.
Under Release 2.0 of the PCMCIA standards, in effect through 1994 and under which many currently used computers were designed, an 8 bit or 16 bit bus was used. Four ground pins, two power pins and up to three free signal pins were available. Under this standard, bandwidth is effectively restricted to about 20 MHz. Power, restricted to two pins, is also limited to around 3.3 watts. These restrictions come about as a result of the limited pin configuration.
The new PC Card Standard released in 1995 improves performance using 32-bit CardBus busmastering thereby increasing bandwidth to 33 MHz, however bandwidth and power are still limited by the connector pin configuration. Changing the existing pin configuration will almost certainly result in a design that is not backward-compatible with the present standard.
Various methods have been employed to overcome the physical size limitations and the electrical connection restrictions inherent in thin architecture expansion cards such as those conforming to the PC Card Standard.
One known method of overcoming the connection restrictions utilizes a modified socket or header within the host device which communicates with additional contacts on the top or bottom of the card near the connector end. The problem with this approach is that it requires a non-standard connector inside the host device. This approach also lacks backward-compatibility in that it cannot be implemented with current sockets.
Another attempted solution to the above-related problems is an end-mounted adapter which connects to two cards at once thereby combining them and at least partially overcoming some of the physical size limitations of the standard. This approach may effectively join two cards in order to increase the size limitation of a single device, but known methods of accomplishing this end all employ adapters or extensions which protrude outside the form factor established in the standard. This solution provides for devices that need more space, but most of these devices are bulky and their portions which extend outside the prescribed form factor often must be removed in order to store the host computer or device. That is, a host computer will not fit into its carrying case or other luggage while the protruding adapter is attached. This situation requires removal of the device from the computer after each use, making the device prone to loss or damage. Alternatively, a specialized carrying case may be used, however this is an added inconvenience and expense and makes the host device bulkier and more difficult to transport.
The present invention provides a means for expanding a single device or combination of devices from one standard format card into another standard format card. The present invention utilizes novel electrical connections between two or more standard cards in order to interconnect the circuitry and devices on the cards and allow hardware and circuitry on one card to be utilized by the other. This inter-card connectivity is achieved while substantially maintaining the prescribed form factor of the card standard.
Some embodiments of the present invention allow for the use of antennas, thin profile connectors such as the XJACK(copyright), cord reels and electronic devices that may work in conjunction with the primary electronic device. Devices which may be used in the interconnecting cards of the present invention include, but are not limited to data/voice radios, AMPS or PCS cellular devices, CDPD or RAM data, IIS band modems, IEEE 802.11 wireless LAN and others.
Embodiments of the present invention comprise one or more electrical connections between one or more thin architecture expansion cards. Cards conforming to the PC Card Standard are used in the most common embodiments, however any thin architecture card or adjacently installed card can benefit from the novel connectors of the present invention.
In a typical embodiment of the present invention, a host computer or device has a series of card slots arranged adjacently so that expansion cards are stacked one atop the other with each card roughly forming a plane substantially parallel with those of the other cards. These slots may be disposed so as to stack the cards horizontally, vertically or in any other orientation so long as the cards are substantially parallel and in close proximity. A host device will have rails, guides or other structure to aid insertion of the cards and maintain the cards in a fixed position. The host device will also have an electrical connector, typically defined by a card standard, such as the 68-pin connector used under the PC Card Standard, for each card. This combination of guiding and retention structure and electrical connector comprises a card socket.
Thin architecture expansion cards have corresponding connectors that mate with those of the host device. The cards of the present invention also have interconnecting connectors which provide an electrical connection directly between the adjacent cards allowing the cards to communicate directly and share resources. The connectors or contacts of the present invention differ from known connection methods because they work well in the confined space between adjacent thin architecture cards. Known connectors such as ribbon cables, etc will not fit in such a confined space.
These interconnecting connectors may be formed by providing conductive contact areas or contacts along the top or bottom of a first card. An adjacent card will have protruding conductors oriented to align with the contacts or contact areas of the first card when the adjacent card is inserted into a slot adjacent to the first card. When both cards have been fully inserted into adjacent slots the protruding contacts of the adjacent card connect with the contact areas of the first card thereby completing their interconnection and allowing the two cards to communicate and share resources.
These connections, used between adjacent expansion cards with contacts, conductors or otherwise, may be referred to as inter-card contacts. The connection effectuated thereby may be referred to as inter-card connector.
It is to be understood that the interconnection of two expansion cards may allow one card to utilize another card""s standard connection interface with the host device as well as resources on the card itself.